This invention relates generally to the field of automotive lighting. More specifically, this invention relates to the field of daytime running lights for automobiles and trucks and the use of light emitting diodes in such lights.
Typical automotive lights utilize incandescent lights as the illuminating element of headlights, daytime running lamps, and other various marker or turn signal lamps. The problem with the use of incandescent bulbs is the relatively short life span of such bulbs. A typical lifetime for incandescent bulbs is 1,000 hours of use. Replacing incandescent bulbs results in down time and inefficiencies in terms of use of the vehicle. The need for replacing incandescent bulbs becomes especially problematic with respect to daytime running lamps. These lamps are constantly in use, unlike the intermittent use of the incandescent bulbs in the other types of lamps. While the lifetime for the incandescent bulbs is the same in terms of overall hours of use, because of the constant use of the daytime running lamps, the incandescent bulbs used in the daytime running lamps need to be replaced more often. This creates a greater expense for the owners and operators of vehicles utilizing such lamps, as well as the manufacturer of the lamps, should the lamps need to be replaced within any warranty period.
Light emitting diodes (LEDs) have a longer lifetime than incandescent bulbs. The typical lifetime of a light emitting diode is approximately 50,000 hours before replacement of the LED is necessary. Thus, it is desirable to replace the incandescent bulbs with LEDs in lamps used on vehicles, such as daytime running lamps, stop lamps, front and rear turn signal lamps, and parking lamps. This type of replacement has not been feasible because the typical LED does not produce enough light to meet governmental standards in terms of luminous intensity for use on automobiles and trucks. In addition, typical LEDs do not emit light over as wide a horizontal and vertical range, as do incandescent bulbs nor do they emit as great a quantity of light. This reduced light emission range and intensity requires the use of large arrays of individual LEDs to produce light over the same emission range as incandescent bulbs.
Moreover, some vehicle owners and operator prefer the look of the incandescent lamp over that of a LED lamp. Through the lens of a typical LED based lamp, one can see the light emitted from individual LEDs. By contrast, light emitted from lamps using incandescent bulbs appear to be more uniformly distributed. This invention solves the above-identified problems associated with the use of incandescent bulbs in lamps such as parking lamps, daytime running lamps, and stop and turn signal lamps, while at the same time providing the look and feel, from the viewers"" perspective, of an incandescent lamp.
Daytime running lamps must meet certain standards in order to be used on automobiles and tractor-trailers. The U.S. Department of Transportation (xe2x80x9cDOTxe2x80x9d) promulgates these standards as set forth in FMVSS 108. FMVSS 108 has adopted SAE Recommended Practices; but not necessarily the most recent revisions of these standards. Additional standards or recommended practices are promulgated by the Society of Automotive Engineers (xe2x80x9cSAExe2x80x9d). The most recent SAE standards or recommended practices are typically more stringent than the standards referenced and promulgated by the DOT. Thus, if a light meets the SAE standards, the same lamp will almost always meet the DOT standards. The SAE Recommended Practice defines a daytime running lamp as a steady burning lamp that is used to improve the conspicuity of a vehicle from the front when the regular headlamps are not required for driving. The light output requirements for daytime running lamps, as described in the SAE Recommended Practice SAE J2087, are as follows:
1) the minimum candela power as measured from the center point of the lamp must be 500. The reader should note that the SAE Recommended Practice details other measurement points and the required minimum candela power. However, the luminous intensity as measured from the center point of the lamp is the highest required minimum;
2) the colors are selected from the following group of colors: white, white to yellow, white to selective yellow, yellow, or selective yellow; and,
3) the daytime running lamp shall have a minimum unobstructed effective projected luminous lens area of 40 cm2. In addition, the daytime running lamp must provide an unobstructed view of the outer lens surface area of at least 10 cm2 measured at 45 degrees to the longitudinal axis of the vehicle.
The DOT regulations require that a daytime running lamp has a luminous intensity not less than 500 candela at test point H-V (the center of the lamp), nor more than 3,000 candela at any location in the beam. The color or frequency of the emitted light may be selected from the group: white, white to yellow, white to selective yellow, selective yellow, or yellow. Any LED light assembly must meet such DOT standards in order to be used on automobiles, trucks, tractor-trailers and other commercial vehicles. Preferably, the automobiles, trucks and tractor-trailers will also meet the SAE Recommended Practice guidelines.
Stop lamps and front and rear turn signal lamps (collectively referred to as indicator lamps) also must meet certain standards in order to be used on automobiles and tractor-trailers. The SAE standard directed to indicator lamps is SAE J2261. The requirements for indicator lamps on vehicles over 80 inches (2032 mm) in width, as described in the SAE Standard SAE J2261, are as follows:
1) for the front turn signal lamp, the minimum luminous intensity as measured from the center point of the lamp is 200 candela. The SAE Standard details other measurement points and the required minimum candela. However, the luminous intensity as measured from the center point of the lamp is the highest required minimum candle power;
2) for the rear stop or turn signal lamp, the minimum luminous intensity as measured from the center point of the lamp is 80 candela;
3) for the yellow turn signal lamp, the minimum luminous intensity as measured from the center point of the lamp is 130 candela;
4) the color of the front turn signal lamp shall be yellow;
5) the color of the rear-turn signal lamp may be red or yellow;
6) the color of the rear stop lamp shall be red; and,
7) the effective projected luminous lighted area of a lamp shall be at least 75 cm2.
Vehicles under 80 inches wide must meet different standards, including SAE J568 for stop lamps, J588 for turn signals, and J319 for rear fog lamps. It should be noted that if the lamps meet SAE Standard J2261, the lamps would meet SAE Standards J568, J588, and J319.
Parking lamps, too, must meet certain standards in order to be used on automobiles and tractor-trailers. The SAE standard directed to parking lamps is SAE J222. The requirements for parking lamps, as described in the SAE Standard SAE J222 are as follows:
1) the minimum luminous intensity as measured from the center point of the lamp is 16.8 candela. The SAE Standard details other measurement points and the required minimum candela. However, the luminous intensity as measured from the center point of the lamps is the highest required minimum candela;
2) the color of the parking light may be white or yellow; and,
3) the lamp must provide a minimum of 13 cm2 of unobstructed projected area from measurable directions.
The above requirements must be met by any light emitting diode lamp assembly that is designed to replace an incandescent bulb assembly for parking lamps, stop and turn lamps, and daytime running lamps.
The light assembly of the instant invention includes light emitting diodes (LEDs) especially suited for use in a daytime running lamp. A catadioptric light assembly is that which both reflects and refracts light. The catadioptric light assembly of the instant invention further includes a control circuit board, a first set of LEDs secured to a first board. A first collimator is disposed in line with the first set of LEDs so as to direct the emitted light to a contoured reflective surface. The contoured reflective surface directs the emitted light to a parabolic reflective surface that re-directs the emitted light, in parallel rays, to a lens. The instant invention also utilizes a second set of LEDs secured to a second board. A second collimator is disposed in line with the second set of LEDs so as to direct the emitted light from the second set of LEDs to the lens. First and second support members are adapted to receive the first and second boards, respectively. The first and second support members also function as heat sinks so as to absorb and remove the heat generated by the LEDs. In a preferred embodiment, the catadioptric light assembly also includes a housing in the shape of a parabolic reflector having a parabolic reflecting surface disposed on the inside of the housing that houses the boards, the circuit board, and the collimators. A lens is disposed in front of the second collimator and adapted to fit within an opening in the housing.
It is an object of this invention to provide a light emitting diode assembly that is suitable to replace an incandescent lamp assembly for use in a daytime running lamp.
It is an additional object of this invention to provide a light emitting diode assembly that, when energized, provides illumination without the spottiness that is typically associated with LED lamps.
It is also an object of this invention to provide a light emitting diode assembly that is practical and cost effective in comparison to an incandescent bulb assembly.
It is a further object of this invention to provide a light emitting diode assembly that appears, from the perspective of a viewer, to be a lamp with the same illumination effect over the same area as an incandescent bulb assembly.
It is also an object of this invention to provide a light emitting diode assembly for use as a parking lamp.
It is further an object of this invention to provide a light emitting diode assembly for use as a stop lamp, as well as a front and rear turn signal lamp.
Additionally, it is an object of this invention to provide a light emitting diode assembly that meets governmental and SAE standards for use as a stop lamp and front and rear turn signal lamp.
It is also an object of this invention to provide a light emitting diode assembly that meets governmental standards for use as a parking lamp.
It is further an object of this invention to provide a light emitting diode assembly that meets governmental standards and SAE standards for use as a daytime running lamp.